本文主要研究内容
作者刘娟娟(2019)在《铁(氢)氧化物纳米颗粒的团聚行为及其机理研究》一文中研究指出:铁(氢)氧化物纳米颗粒因其具有特殊的反应活性,易于吸附环境中的有机物和重金属离子,常被作为吸附剂和催化剂等广泛地应用于环境污染修复领域。但铁(氢)氧化物纳米颗粒在环境中易水解形成沉淀,团聚作用作为一种常见的沉淀形式,已成为研究纳米颗粒对各类污染物稳定性影响的最佳方法。磁铁矿纳米颗粒(MNPs)和水铁矿纳米颗粒(FNPs)普遍存在于水环境中,其具有比表面积大、氧化还原反应性好、吸附能力强、无毒且易合成等优点。由于MNPs极易发生团聚作用,常在其表面包覆有机物增强了稳定性,而FNPs常掺杂有多种金属离子。因此,查明包覆有机物的MNPs和掺杂重金属的FNPs在自然环境中团聚行为及其机理对于进一步理解环境污染物的行为过程具有重要的意义。本研究采用共沉淀的方法,合成了包覆3种不同种类有机酸(柠檬酸、聚丙烯酸和乙酸)的磁铁矿纳米颗粒、水铁矿纳米颗粒和掺杂4种重金属(Pb、Mn、Al和Cr)的水铁矿纳米颗粒。借助动态光散射(DLS)测定了合成的纳米颗粒粒径的动态变化,较为系统地比较了各纳米颗粒在不同pH(5.0~9.0)、离子强度(0.03~1400 mmol·L-1)、电解质类型(NaCl、CaCl2、Na2SO4和NaH2PO4/Na2HPO4)、有机质种类(胡敏酸、富里酸和CH3COONa)及含量等因素下的团聚行为及其差异。另外,通过纳米颗粒的zeta电位的测定、吸附试验和临界聚沉浓度(CCC)的计算,并结合Derjaguin-Landau-Verwey-Overbeek(DLVO)理论揭示了其团聚机理。旨在探究不同种类的铁(氢)氧化物纳米颗粒在水环境中的稳定性,为很更好地预测无机和有机污染物在环境中的迁移和归宿提供理论依据。得到的主要研究结果如下:1.明确了在自然和工程水环境的pH范围内(5.0~9.0)包覆柠檬酸(CA)、聚丙烯酸(PAA)和乙酸(AA)后对磁铁矿纳米颗粒(MNPs)稳定性的影响。在pH为5.0~9.0的范围内,包覆CA、PAA和AA后MNPs的zeta电位均为负值,且表面的负电荷量均较纯MNPs增多,从而增加了MNPs在自然水体环境中的稳定性。3种有机酸对MNPs的zeta电位的影响由强到弱依次为:PAA>CA>AA,这与各种有机酸中含有的羧基(-COOH)官能团的数量成正比。相同pH条件下,包覆3种有机酸均导致MNPs表面的等电点(pHIEP)降低,pHIEP和zeta电位均呈现由低到高依次为PAA-MNPs<CA-MNPs<AA-MNPs。2.探明了不同种类的电解质溶液及离子强度对CA、PAA和AA包覆的MNPs稳定性的影响。在相同电解质溶液中,包覆3种有机酸的MNPs的团聚行为基本相同,且其稳定性均随着离子强度的增加而减弱,这与离子强度增加导致MNPs的双电层被压缩,且zeta电位降低加速了团聚有关。在相同pH(5.0±0.2和7.0±0.2)和离子强度条件下,包覆3种有机酸的MNPs在一价阳离子(Na+)溶液中的稳定性大于二价阳离子(Ca2+)溶液,这是由于Ca2+与MNPs表面的-COOH间存在着吸附或键桥作用,导致其显著地中和了MNPs表面的电荷,从而促进其团聚。另外,MNPs在Ca2+和Na+溶液中CCC的比值(Ca2+/Na+)大约在2-6左右,且符合Schulze-Hardy规则。在pH=7.0±0.2时,较低离子强度下,不同价态阴离子对有机酸包覆的MNPs稳定性的影响不尽相同,其由强到弱依次为:PO43->SO42->Cl-,这与其CCC值的大小趋势一致。可见阴离子价态越高及吸附能力越强,MNPs的稳定性越强。另外,包覆3种有机酸的MNPs的团聚行为和计算的CCC值均与DLVO理论相吻合。3.证实了天然有机质胡敏酸(HA)的存在对含有电解质溶液的CA-MNPs、PAA-MNPs和AA-MNPs团聚行为的抑制作用。在pH=7.0±0.2时,加入浓度为2 mg C·L-1的HA,可以显著抑制包覆3种有机酸的MNPs在不同电解质溶液中的团聚行为。这是由于HA吸附在MNPs的表面,增加了其粒径和表面负电荷量,导致MNPs之间的静电排斥力和空间排斥力增强,从而提高了其在不同电解质溶液中的稳定性。4.采用动态光散射(DLS)探明了水铁矿纳米颗粒(FNPs)在不同种类和含量有机质存在时的团聚行为及机理。胡敏酸(HA)、富里酸(FA)和醋酸钠(CH3COONa)有机物存在时,由于有机物的-COOH官能团吸附到FNPs的表面且发生了去质子化作用,使得纳米颗粒表面带有更多的负电荷,导致水铁矿纳米颗粒(FNPs)的pHIEP均从中性下降为酸性。另外,C/Fe比率越大,被吸附的有机物越多,导致FNPs的pHIEP越低。相同C/Fe比率时,FA/HA对FNPs的pHIEP改变大于CH3COONa。在pH中性条件下,当加入的HA/FA的浓度大于0.5 mg C·L-1时能显著抑制FNPs的团聚,但CH3COONa却未发现这种现象,这主要是与FNPs之间的空间或静电相互作用因有机物pKa和分子量的不同而异有关。5.利用FT-IR查明了Na2SO4的存在时导致FNPs发生快速团聚的原因。在酸性和中性pH条件下,Na2SO4的存在时,FNPs的zeta电位在pH 2~10的范围内和不同离子强度下(0.01~100 mmol·L-1)均呈现中性,这与FNPs发生相变生成了施氏矿物(Schwertmannite),且SO42-离子被吸附在施氏矿物表面有关。另外,该相变过程导致FNPs在硫酸盐存在时均迅速发生团聚。在酸性和中性pH条件下,掺杂重金属Pb、Mn、Al和Cr后FNPs在Na2SO4存在时的团聚行为与纯FNPs的结果相一致。6.明确了掺杂重金属Pb、Mn、Al和Cr的水铁矿纳米颗粒(Mt-FNPs)在酸性和中性pH条件下,不同种类电解质溶液存在时的团聚行为及差异。在NaCl和CaCl2存在时,4种Mt-FNPs在酸性pH条件下(pH=5.0±0.1),反应5 min内粒径都稳定在20 nm左右;而其在中性pH条件下均迅速发生团聚,且5 min内粒径维持在200~600nm的范围。这主要与4种Mt-FNPs的pHIEP范围为7.6~8.8,而中性条件比较接近其pHIEP有关。当CH3COONa存在时,4种Mt-FNPs不论是在酸性还是中性pH条件下均迅速地发生团聚,且在中性pH条件下其团聚速率较大。但在相同pH和电解质溶液中,Pb-FNPs、Mn-FNPs、Al-FNPs、Cr-FNPs和FNPs之间的团聚行为相似。综上所述,水环境中铁(氢)氧化物纳米颗粒的团聚行为受到溶液pH、离子强度、电解质溶液、有机质种类及含量等因素的影响,也与共存的有机酸和金属离子的种类密切相关。去质子化作用、吸附作用、键桥作用、表面相变等过程可以改变铁(氢)氧化物纳米颗粒之间的静电排斥力和空间排斥力的强弱,从而影响其稳定性。
Abstract
tie (qing )yang hua wu na mi ke li yin ji ju you te shu de fan ying huo xing ,yi yu xi fu huan jing zhong de you ji wu he chong jin shu li zi ,chang bei zuo wei xi fu ji he cui hua ji deng an fan de ying yong yu huan jing wu ran xiu fu ling yu 。dan tie (qing )yang hua wu na mi ke li zai huan jing zhong yi shui jie xing cheng chen dian ,tuan ju zuo yong zuo wei yi chong chang jian de chen dian xing shi ,yi cheng wei yan jiu na mi ke li dui ge lei wu ran wu wen ding xing ying xiang de zui jia fang fa 。ci tie kuang na mi ke li (MNPs)he shui tie kuang na mi ke li (FNPs)pu bian cun zai yu shui huan jing zhong ,ji ju you bi biao mian ji da 、yang hua hai yuan fan ying xing hao 、xi fu neng li jiang 、mo du ju yi ge cheng deng you dian 。you yu MNPsji yi fa sheng tuan ju zuo yong ,chang zai ji biao mian bao fu you ji wu zeng jiang le wen ding xing ,er FNPschang can za you duo chong jin shu li zi 。yin ci ,cha ming bao fu you ji wu de MNPshe can za chong jin shu de FNPszai zi ran huan jing zhong tuan ju hang wei ji ji ji li dui yu jin yi bu li jie huan jing wu ran wu de hang wei guo cheng ju you chong yao de yi yi 。ben yan jiu cai yong gong chen dian de fang fa ,ge cheng le bao fu 3chong bu tong chong lei you ji suan (ning meng suan 、ju bing xi suan he yi suan )de ci tie kuang na mi ke li 、shui tie kuang na mi ke li he can za 4chong chong jin shu (Pb、Mn、Alhe Cr)de shui tie kuang na mi ke li 。jie zhu dong tai guang san she (DLS)ce ding le ge cheng de na mi ke li li jing de dong tai bian hua ,jiao wei ji tong de bi jiao le ge na mi ke li zai bu tong pH(5.0~9.0)、li zi jiang du (0.03~1400 mmol·L-1)、dian jie zhi lei xing (NaCl、CaCl2、Na2SO4he NaH2PO4/Na2HPO4)、you ji zhi chong lei (hu min suan 、fu li suan he CH3COONa)ji han liang deng yin su xia de tuan ju hang wei ji ji cha yi 。ling wai ,tong guo na mi ke li de zetadian wei de ce ding 、xi fu shi yan he lin jie ju chen nong du (CCC)de ji suan ,bing jie ge Derjaguin-Landau-Verwey-Overbeek(DLVO)li lun jie shi le ji tuan ju ji li 。zhi zai tan jiu bu tong chong lei de tie (qing )yang hua wu na mi ke li zai shui huan jing zhong de wen ding xing ,wei hen geng hao de yu ce mo ji he you ji wu ran wu zai huan jing zhong de qian yi he gui su di gong li lun yi ju 。de dao de zhu yao yan jiu jie guo ru xia :1.ming que le zai zi ran he gong cheng shui huan jing de pHfan wei nei (5.0~9.0)bao fu ning meng suan (CA)、ju bing xi suan (PAA)he yi suan (AA)hou dui ci tie kuang na mi ke li (MNPs)wen ding xing de ying xiang 。zai pHwei 5.0~9.0de fan wei nei ,bao fu CA、PAAhe AAhou MNPsde zetadian wei jun wei fu zhi ,ju biao mian de fu dian he liang jun jiao chun MNPszeng duo ,cong er zeng jia le MNPszai zi ran shui ti huan jing zhong de wen ding xing 。3chong you ji suan dui MNPsde zetadian wei de ying xiang you jiang dao ruo yi ci wei :PAA>CA>AA,zhe yu ge chong you ji suan zhong han you de suo ji (-COOH)guan neng tuan de shu liang cheng zheng bi 。xiang tong pHtiao jian xia ,bao fu 3chong you ji suan jun dao zhi MNPsbiao mian de deng dian dian (pHIEP)jiang di ,pHIEPhe zetadian wei jun cheng xian you di dao gao yi ci wei PAA-MNPs<CA-MNPs<AA-MNPs。2.tan ming le bu tong chong lei de dian jie zhi rong ye ji li zi jiang du dui CA、PAAhe AAbao fu de MNPswen ding xing de ying xiang 。zai xiang tong dian jie zhi rong ye zhong ,bao fu 3chong you ji suan de MNPsde tuan ju hang wei ji ben xiang tong ,ju ji wen ding xing jun sui zhao li zi jiang du de zeng jia er jian ruo ,zhe yu li zi jiang du zeng jia dao zhi MNPsde shuang dian ceng bei ya su ,ju zetadian wei jiang di jia su le tuan ju you guan 。zai xiang tong pH(5.0±0.2he 7.0±0.2)he li zi jiang du tiao jian xia ,bao fu 3chong you ji suan de MNPszai yi jia yang li zi (Na+)rong ye zhong de wen ding xing da yu er jia yang li zi (Ca2+)rong ye ,zhe shi you yu Ca2+yu MNPsbiao mian de -COOHjian cun zai zhao xi fu huo jian qiao zuo yong ,dao zhi ji xian zhe de zhong he le MNPsbiao mian de dian he ,cong er cu jin ji tuan ju 。ling wai ,MNPszai Ca2+he Na+rong ye zhong CCCde bi zhi (Ca2+/Na+)da yao zai 2-6zuo you ,ju fu ge Schulze-Hardygui ze 。zai pH=7.0±0.2shi ,jiao di li zi jiang du xia ,bu tong jia tai yin li zi dui you ji suan bao fu de MNPswen ding xing de ying xiang bu jin xiang tong ,ji you jiang dao ruo yi ci wei :PO43->SO42->Cl-,zhe yu ji CCCzhi de da xiao qu shi yi zhi 。ke jian yin li zi jia tai yue gao ji xi fu neng li yue jiang ,MNPsde wen ding xing yue jiang 。ling wai ,bao fu 3chong you ji suan de MNPsde tuan ju hang wei he ji suan de CCCzhi jun yu DLVOli lun xiang wen ge 。3.zheng shi le tian ran you ji zhi hu min suan (HA)de cun zai dui han you dian jie zhi rong ye de CA-MNPs、PAA-MNPshe AA-MNPstuan ju hang wei de yi zhi zuo yong 。zai pH=7.0±0.2shi ,jia ru nong du wei 2 mg C·L-1de HA,ke yi xian zhe yi zhi bao fu 3chong you ji suan de MNPszai bu tong dian jie zhi rong ye zhong de tuan ju hang wei 。zhe shi you yu HAxi fu zai MNPsde biao mian ,zeng jia le ji li jing he biao mian fu dian he liang ,dao zhi MNPszhi jian de jing dian pai chi li he kong jian pai chi li zeng jiang ,cong er di gao le ji zai bu tong dian jie zhi rong ye zhong de wen ding xing 。4.cai yong dong tai guang san she (DLS)tan ming le shui tie kuang na mi ke li (FNPs)zai bu tong chong lei he han liang you ji zhi cun zai shi de tuan ju hang wei ji ji li 。hu min suan (HA)、fu li suan (FA)he cu suan na (CH3COONa)you ji wu cun zai shi ,you yu you ji wu de -COOHguan neng tuan xi fu dao FNPsde biao mian ju fa sheng le qu zhi zi hua zuo yong ,shi de na mi ke li biao mian dai you geng duo de fu dian he ,dao zhi shui tie kuang na mi ke li (FNPs)de pHIEPjun cong zhong xing xia jiang wei suan xing 。ling wai ,C/Febi lv yue da ,bei xi fu de you ji wu yue duo ,dao zhi FNPsde pHIEPyue di 。xiang tong C/Febi lv shi ,FA/HAdui FNPsde pHIEPgai bian da yu CH3COONa。zai pHzhong xing tiao jian xia ,dang jia ru de HA/FAde nong du da yu 0.5 mg C·L-1shi neng xian zhe yi zhi FNPsde tuan ju ,dan CH3COONaque wei fa xian zhe chong xian xiang ,zhe zhu yao shi yu FNPszhi jian de kong jian huo jing dian xiang hu zuo yong yin you ji wu pKahe fen zi liang de bu tong er yi you guan 。5.li yong FT-IRcha ming le Na2SO4de cun zai shi dao zhi FNPsfa sheng kuai su tuan ju de yuan yin 。zai suan xing he zhong xing pHtiao jian xia ,Na2SO4de cun zai shi ,FNPsde zetadian wei zai pH 2~10de fan wei nei he bu tong li zi jiang du xia (0.01~100 mmol·L-1)jun cheng xian zhong xing ,zhe yu FNPsfa sheng xiang bian sheng cheng le shi shi kuang wu (Schwertmannite),ju SO42-li zi bei xi fu zai shi shi kuang wu biao mian you guan 。ling wai ,gai xiang bian guo cheng dao zhi FNPszai liu suan yan cun zai shi jun xun su fa sheng tuan ju 。zai suan xing he zhong xing pHtiao jian xia ,can za chong jin shu Pb、Mn、Alhe Crhou FNPszai Na2SO4cun zai shi de tuan ju hang wei yu chun FNPsde jie guo xiang yi zhi 。6.ming que le can za chong jin shu Pb、Mn、Alhe Crde shui tie kuang na mi ke li (Mt-FNPs)zai suan xing he zhong xing pHtiao jian xia ,bu tong chong lei dian jie zhi rong ye cun zai shi de tuan ju hang wei ji cha yi 。zai NaClhe CaCl2cun zai shi ,4chong Mt-FNPszai suan xing pHtiao jian xia (pH=5.0±0.1),fan ying 5 minnei li jing dou wen ding zai 20 nmzuo you ;er ji zai zhong xing pHtiao jian xia jun xun su fa sheng tuan ju ,ju 5 minnei li jing wei chi zai 200~600nmde fan wei 。zhe zhu yao yu 4chong Mt-FNPsde pHIEPfan wei wei 7.6~8.8,er zhong xing tiao jian bi jiao jie jin ji pHIEPyou guan 。dang CH3COONacun zai shi ,4chong Mt-FNPsbu lun shi zai suan xing hai shi zhong xing pHtiao jian xia jun xun su de fa sheng tuan ju ,ju zai zhong xing pHtiao jian xia ji tuan ju su lv jiao da 。dan zai xiang tong pHhe dian jie zhi rong ye zhong ,Pb-FNPs、Mn-FNPs、Al-FNPs、Cr-FNPshe FNPszhi jian de tuan ju hang wei xiang shi 。zeng shang suo shu ,shui huan jing zhong tie (qing )yang hua wu na mi ke li de tuan ju hang wei shou dao rong ye pH、li zi jiang du 、dian jie zhi rong ye 、you ji zhi chong lei ji han liang deng yin su de ying xiang ,ye yu gong cun de you ji suan he jin shu li zi de chong lei mi qie xiang guan 。qu zhi zi hua zuo yong 、xi fu zuo yong 、jian qiao zuo yong 、biao mian xiang bian deng guo cheng ke yi gai bian tie (qing )yang hua wu na mi ke li zhi jian de jing dian pai chi li he kong jian pai chi li de jiang ruo ,cong er ying xiang ji wen ding xing 。
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论文作者分别是来自西北农林科技大学的刘娟娟,发表于刊物西北农林科技大学2019-07-11论文,是一篇关于铁氢氧化物纳米颗粒论文,团聚论文,动态光散射论文,临界聚沉浓度论文,理论论文,西北农林科技大学2019-07-11论文的文章。本文可供学术参考使用,各位学者可以免费参考阅读下载,文章观点不代表本站观点,资料来自西北农林科技大学2019-07-11论文网站,若本站收录的文献无意侵犯了您的著作版权,请联系我们删除。
标签:铁氢氧化物纳米颗粒论文; 团聚论文; 动态光散射论文; 临界聚沉浓度论文; 理论论文; 西北农林科技大学2019-07-11论文;